The heart is a hollow, muscular organ in vertebrates responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in annelids, mollusks, and arthropods. The term cardiac (as in cardiology) means "related to the heart" and comes from the Greek καρδιά, kardia, for "heart."

early development

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At 21 days after conception, the human heart rate begins beating at 75-80 beats per minute and accelerates linearly for the first month of beating.The human embryonic heart (EHR) begins beating at approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy. The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (bpm). It then accelerates linearly for the first month of beating, peaking at 165-185 bpm during the early 7th week, (early 9th week after the LMP). This acceleration is approximately 3.3 bpm per day, or about 10 bpm every three days, an increase of 100 bpm in the first month. ^*

After peaking at about 9.2 weeks after the LMP, it decelerates to about 150 bpm (+/-25 bpm) during the 15 week after the LMP. After the 15th week the deceleration slows reaching an average rate of about 145 (+/-25 bpm) bpm at term. The regression formula which describes this acceleration before the embryo reaches 25 mm in crown-rump length or 9.2 LMP weeks is:

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I'm a southern girl at heart!
sillysockmonkey (Ilia Awald) Wed, 16 Dec 2009 04:37:03 -0000
I'm a southern girl at heart!
@jinormous I think @annaleekeefer is a southern girl at heart. Re: sugarpie. :)
mscantling (Mark Scantling) Wed, 16 Dec 2009 02:56:12 -0000
@jinormous I think @annaleekeefer is a southern girl at heart. Re: sugarpie. :)
well this made my heart swell ---Learning about Southern layer cakes http://bit.ly/4XojiE /via @nytimesfood
ddot_ (deborah) Wed, 16 Dec 2009 01:19:48 -0000
well this made my heart swell ---Learning about Southern layer cakes http://bit.ly/4XojiE /via @nytimesfood
Why u so obsessed with me? 5'8 brown eyed goddes 160lbs all natural beauty with brains southern girl with a big heart I would b 2 I heart me
GAGirl87 (Nashia Mayfield) Wed, 16 Dec 2009 00:57:08 -0000
Why u so obsessed with me? 5'8 brown eyed goddes 160lbs all natural beauty with brains southern girl with a big heart I would b 2 I heart me
@cwm76 Ok southern girl's secret to open heart surgery mac and cheese: Asiago.It puts an edge on it.You can still jack and ched. Add asiago.
DamiOrjo (Em) Wed, 16 Dec 2009 00:54:16 -0000
@cwm76 Ok southern girl's secret to open heart surgery mac and cheese: Asiago.It puts an edge on it.You can still jack and ched. Add asiago.
I love meeting with couples where the man was raised to be a true Southern Gentleman... melts my heart.
lkevents (Lauren Kelly) Tue, 15 Dec 2009 21:23:21 -0000
I love meeting with couples where the man was raised to be a true Southern Gentleman... melts my heart.

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